One of n≥2 servers, connectable via a network, implements a cryptographic protocol using a secret key K which is shared between the n servers, and includes first and second server compartments. The first is connectable to the network, adapted to implement the cryptographic protocol, and stores a current key share of the secret key K. The second is inaccessible from the network in the operation of the server, stores a set of master keys, and is adapted, for each of successive time periods, to unilaterally generate a new key share of the secret key K and to supply it to the first as the current key share for that time period. The new key share includes a random share of a predetermined value p which is shared between the n servers, and the random share includes a function of the set of master keys.
Legal claims defining the scope of protection, as filed with the USPTO.
2. The server as claimed in claim 1 wherein the second server compartment stores the current key share for each time period of the successive time periods and the new key share for each time period comprises a sum of the current key share for an immediately previous time period and the random share δ i .
3. The server as claimed in claim 1 wherein the second server compartment is adapted to generate updated master keys for each of the successive time periods, each updated master key comprising a one-way function of a preceding master key generated for an immediately preceding time period in the successive time periods.
4. The server as claimed in claim 1 wherein the first server compartment comprises a virtual machine on a cloud computing platform.
5. The server as claimed in claim 4 wherein the first server compartment comprises a fresh virtual machine for each time period of the successive time periods.
6. The server as claimed in claim 1 wherein the predetermined value p=0.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
March 17, 2018
January 15, 2019
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